Component for arranging in a fluid circuit between a solar collector and a heat exchanger comprises a forward run tubular section (1) and a return run tubular section (2) formed as a one-piece injection-molded part. Independent claims are also included for the following: (1) Pipe component group containing the above component; and (2) Ventilating arrangement containing the pipe component group. Preferred Features: The forward run and a return run tubular sections are connected in a lower region using a connecting element (3) formed as one piece with both tubular sections. The connecting element has a flat part provided with markings.
